18 BULLETIN 173, U. S. DEPARTMENT OF AGRICULTURE. 



portion of the fruit unmarketable. Plate V, figures 1 and 2, shows 

 photographs of sprayed and unsprayed prunes, the prunes having 

 been picked from trees when full grown. Robe de Sargent prunes 

 blossom about the same time as French prunes, and are injured to 

 the same extent as that variety. 



INJURY TO CHERRIES. 



Cherries, as a whole, are not injured so severely by the feeding of a 

 given number of adults as would be the case for the same number of 

 thrips upon pears and prunes, but certain varieties, especially the 

 black cherries, suffer comparatively as much from a monetary stand- 

 point as either pears or prunes. Probably the worst damage accom- 

 plished on cherries is by the deposition of eggs in the long fruit stems 

 and in the leaves, and by the feeding of the larvae upon the foliage. 

 The deposition of eggs in the fruit stems has at times caused a large 

 percentage of the cherry crop to drop, and it is a common sight to 

 see the foliage entirely riddled by the larvae, thus greatly weakening 

 the trees. Many other instances are on record where the adults 

 have injured the fruit buds to such an extent that only a few blos- 

 soms appeared. Late varieties of cherries, such as the Royal Anne, 

 escape serious injury more than the earlier blooming black varieties. 

 Fortunately the manner of bud growth and blossoming of cherries 

 permits effective penetration of different spray solutions more ad- 

 vantageously than is the case with either pears or prunes. 



INJURY TO APPLES. 



While there are not many instances of great commercial injury to 

 apples, yet individual cases have been known where the adult thrips 

 have killed all of the buds in the cluster except the central one. This 

 was especially noticeable in an orchard of the Xewtown Pippin variety 

 in the vicinity of San Jose in 1910. Some small orchards in Sacra- 

 mento County were rather seriously injured during the same year. 



INJURY TO PEACHES. 



Following the apple, peaches come next in importance as regards 

 possibility of dangerous injury, the early varieties suffering the greater 

 loss. The more seriously injured varieties are the Muir, Xicol-cling, 

 Crawford, Foster, and Lovel, in order of damage done, injury being 

 more severe on the first two varieties mentioned. On account of the 

 hairy pubescence on the young peach fruits, the thrips prefer to feed 

 upon the nectary glands and the inside of the calyx cups; this pre- 

 vents proper pollination, and the young fruits drop to the ground a 

 few weeks after the blossoming period. Where the injury has been 

 severe, peaches are sometimes prevented from blooming, and the larvae 

 feeding upon the tender leaves cause them to curl and become dis- 



